Thermostatic control mechanism



Patented. Mar. 10, 1942 THERMOSTATIC CONTROL MECHANISM Carlton w.Bondurant, Euclid, Ohio, assignor to The Titan Valve & ManufacturingCompany, Cleveland, Ohio, a corporation of Ohio Application December 11,1939, Serial N0. 308,595

2 Claims.

This invention relates to improvements in thermostatic control mechanismand more particularly to one in which two valves are sub.- stantiallysimultaneously controlled to close one as the other is opened and theinvention relates to improved structure whereby the desired results areobtained.

My invention is applicable to a combination of a thermostaticallycontrolled over-center snap acting device and a pair of valvescontrolled thereby to open one valve as the other valve is closed. Oneobject of my invention is to hold one of said valves definitely closeduntil the overcenter device has passed a central balanced position andis ready to snap over center.

Another object of my invention is to provide a lost motion connectionbetween the valves so that one valve may remain closed while the snapacting device is approaching and passing its central or snap-overposition, after which both valves move quickly during the snap action.

Another object of the present invention is to provide a novelcombination between a pair of thermostatically controlled valves and adiaphragm valve so that movement of the diaphragm valve is efiicientlycontrolled by the thermostatic device without unnecessary loss of gasused in the control operation, and to prevent undesired movements of thediaphragm valve.

Other objects and advantages of the present invention will be apparentfrom the accompany- -ing drawing and description and the essentialfeatures will be set forth in the claims.

- In the drawing, Fig. 1 is a diagrammatic view showing the combinationbetween a diaphragm valve and my improved thermostatically controlleddevice, most of the parts being cut away or in section to more clearlyshow the operation thereof Fig. 2 is an enlarged view of a portion ofthe mechanism of Fig. 1; while Fig. -3 is a view similar to Fig. 2showing the position of the parts after the-snap acting device has movedover center to an opposite position.

My invention is particularly applicable for use with a diaphragm valvesuch as that shown and indicated generally at IU comprising a casingdivided into a lower chamber Illa and an'upper chamber lllb by adiaphragm II. The lower chamber is connected in series with a main gassupply line i2 and includes a valve seat l3. A

conduit I4 leads from chamber lllb to a source of gas supply at the samepressure as that in the main [2 and the action of the diaphragm valve asis generally understood is to close against the seat l3 when the gaspressure is equal in chambers Illa and lb. When the pressure is relievedin chamber Illb as by bleeding through conduit It, then the greaterpressure in chamber Illa will open thediaphragm. valve. Those familiarwith this art will realize that one useful application ofthe combinationhere disclosed is the opening and closing of the gas supplythrough'conduit l2 to some heating device in response to movements ofthe thermostat l5 which is subjected to the temperature of some mediumheated by the burner supplied through pipe l2. For instance in a warmair furnace-whose burner is supplied in responseto movements of thediaphragm valve III, the thermostat l5 might be placed in-an air chamberof the furnace in such a manner that when the thermostat I5 is heatedbeyond a predetermined point it will act to close the diaphragm valveand vice versa when the temperature about the thermostat l5 drops belowa predetermined point then the diaphragm valve I0 would be opened toagain supply heat to the furnace. All of this is well known in the priorart and is only mentioned here to illustrate one useful application ofmy improvedv control mechanism.

The thermostatic device here shown comprises a thermostatic element ofwell known type comprising a tube l5ahaving a relatively largecoeflicient of expansion and a rod l5b of material having a relativelysmall coefiicient of expansion. The two are fastened together at the endI50 so that when the tube is cold and contracts, the rod |5b is movedtoward the left, and when the the right as viewed in Fig. 1. The snapacting device controlled by the thermostatic element I comprises aprimary lever I 6 fulcrumed at l6a on an abutment of the casing l1 and asecondary lever l8 which is bifurcated at its lower end and fulcrumed atMa on a pair of laterally spaced abutments I}! on the casing ll. A tension spring 20 is connected between point 2| on lever" and point 22 onlever IS. The spring thus holds each lever against, its fulcrum andholds the lever l8 toward theleft as viewed in Fig. 1 when the lineconnecting points 2| and 22 lies to-the left of point i812. When thelevers move so as to cause the line between points 2i and 22 to move tothe right of point [8a, the

spring 20 causes the lever I8 to snap over center from the fulllineposition of Fig. 1 to the dotdash position there shown. This is a knownform tegral with casing I l) is provided having valved 2 openings 23 and28. Opening 23 is connected by conduit 25 with the gas main l2 andopening 24 leads into the hollow space of casing I! which is providedwith an outletopening and conduit 26. The casing means Ila has a thirdopening 21 which is connected by conduit H with chamber lb of thediaphragm valve. Valves 28 and 29 are provided for controlling theopenings 23 and 24 respectively. These valves are provided with commonconnecting means arranged so that one valve is closed as the other valveis opened. The portion l8b of lever l8 through valve 29 engages thecommon connecting means so as to control the movements of the valves.

The common connecting means for valves 28 and 29 comprises a valve stem38 on which the valve 28 is rigidly mounted. A sleeve 3| fixed to thecasing means Ila guides the stem 38 and serves as an abutment for thecompression spring 32 which engages against the shoulder 28a so as tourge valve 28 toward its seat. Valve 29 has pressed therein a U-shapedwasher 33 which lies in the groove 34 of stem 38 with lost motionlongitudinally of the stem, that is to say, the

washer 3-3 is approximatelymr inch less than the width of the groove 34.A spring 35 lies between the sleeve 3| and valve 29 so as to urge valve29 toward its seat. When the parts are in the position of Fig. 1, theclearance at the point 38 between valve 29 and its seat is greater thanthe lost motion between valve 29 and stem 30, being about one-sixteenthinch. The spring 35 is stronger than the spring 32.

The operation of the device is as follows: With the parts in theposition of Fig. 1, the thermostat I5 is cold, the portion l8b is in itsleft-hand position, valve 29 is open, valve 28 is closed and gas isbeing bled from chamber lllb through concluit l4 and openings 21 and 24to conduit 26 whence it is led away to a point where it is burned,usually by a pilot flame. Thus the diaphragm valve I8 is opened tosupply heat to the device which will heat up the thermostat i5. As thethermostat is heated lever moves counterclockwise carrying the point 22towardthe point l8a. If it were not for the effect of sprin 35 tendingto move lever l8 in a clockwise direction.

, the snap acting device would reach a position of equilibrium whenpoints 2|, l8a. and 22 were in line. However because of the effect ofspring 35,

the snap acting device reaches a position of equilibrium slightly beforethose three points are alined. In any case when the snap acting devicehas reached a position of equilibrium or balance,

then if the thermostat I5 should happen to remain in that position for awhile,the snap acting device might remain near an equilibrium positionwith consequent possibility of valves 28 and 29 being open at the sametime. With my improved device the spring 32 positively seats the valve28 at such a time when the snap acting device is in a substantiallybalanced "central posi tion. Upon further heating of the thermostaticelement lever l8 carries point 22 farther to the right and the snapacting device moves beyond its .central balanced position with the partl8b moving suddenly from the full line position of Fig. 1 to thedot-dash position there shown. Impelled by spring 35, valve 29 movesquickly valve to close.

toward the right causing washer 38 to engage the shoulder lie at theright end of stem 38, whereupon valve 28 is lifted from its seat by theaction 61' spring 38 overcoming the action of spring 32. Thus valves 28and 29 are moved almost instantly from the position of Fig. 2 to that ofFig. 3, thus closing the escape of gas from chamber I8b to the outlet 28and introducing gas from conduit 28 through casing means Ila and conduitl4 to the chamber lllb causing the diaphragm These valves move sosuddenly that there is practically no loss of gas during the instantvalves 28 and 29 areboth open. when the thermostat again cools the snapacting device returns to the position of Fig. 1. with the spring 35holding valves 28 and 29 in their relative position on stem 38 as shownin Fig. 3 until valve 28 is seated and valve 29 is partly opened,

after which further movement of the lever portion l8b fully opens valve29 taking advantage of the lost motion connection between valve 29 andstem 30. 1

What I claim is: 1. Valve control mechanism comprising casing meanshaving first and second valved openings alined in opposite walls of saidcasing means, two valves, one for each opening, said valves seating inopposite directions toward their respective openings, connecting meansfor said valves including a stem providing a lost motion connectionpermitting relative movement between said valves longitudinally of saidstem, abutment means associated with said lost motion connectionpermitting one of said valves to be open when the other valve is closedand preventing both of said valves being closed at once, a lighterspring urging the valve at said first opening toward closed position, aheavier spring urging the valve at said second opening toward closedposition, and an over-center snap acting device controlling said valveat said second opening, said device being adapted to move the said valveagainst the efiect of said heavier spring.

2. Valve control mechanism comprising casing means having openingsproviding two valve seats.

two valves respectively coacting with said seats, said valves closingtoward their respective seats in opposite directions, av spring urgingeach valve toward its seat, a stem connecting said valves and compellingmovement of said valves together, said stem being of such a length thatwhen one valve is closed the other valve is open, one of said valveshaving a lost motion connection with said stem, an over-centerspring-propelled snap acting device for causing opening and closing ofsaid one valve, the lost motion in said lost motion connection beingtaken up when said one valve has moved that distance toward closedposition corresponding to movement of said snap acting device to andslightly beyond center position as the device moves invalve-closing-causing direction.

the spring associated with said one valve being stronger than the springassociated with the other valve, whereby the other of said valves willbe held firmly seated by its spring until said snap device suddenlycauses closing of said one valve and concurrent opening of said othervalve.

' CARLTON W. BONDURANT.

